The proposed work is to study the characteristics of a low molecular weight (MW) zinc binding ligand in tissues, to study the accumulation of zinc in metallothionein (MT) of lamb tissues, to study the influence of age and hormone upon the accumulation of zinc in MT, and to study the influence of stress and age upon the half-life of MT. The low MW zinc binding ligand is present in kidney, pancreas and intestinal mucosa, but not in the liver. This is suggestive that this ligand may be involve in zinc transport. Therefore, we propose to purify and characterize this ligand in order to obtain information on its possible function. Ion exchange and gel filtration chromatography are proposed to be used for this purification. Excess zinc has been shown to accumulate almost exclusively with MT in tissues of rats and chicks. Therefore, plans are to determine whether this is also true for sheep. We have evidence that much more zinc is stored with MT in young animals than in old ones, and this could in part be influenced by hormones. Since stress has been shown to increase the amount of zinc deposited with MT, work is planned to determine whether this is the result of an affect upon the half-life of MT. The influence of age upon the half-life of MT will also be evaluated.